Implements the new general design (thanks to Clement's and Jule's mockup)
Allows the display or the hiding of non-compatible plugins
Add advanced filters in the page (harmonization with the advanced filters in the user manager)
Add the display of a screenshot, the rating and the tags for each plugins
Add Piwigo's Certification levels for each plugins
Add the file admin/themes/default/css/components/general.css to save css compnents that will be used in diffenrent places in the admin
* [header] replace the color switcher by a light/dark (sun/moon) action link
* [footer] add icons for piwigo.org doc & forum
* [footer] replace Piwigo logo with a clean SVG version, created by @mistic100
* [header/footer] remove "|" separators
* [header] limit title display to 50% of page width (with ellipsis on overflow)
* [header] media query to hide link labels below 800px
* [header] switch color of home icon on hover
* on clear theme, change header/footer background color to #333 (dark grey) like on current Piwigo.org
The footer logo was going outside the footer (the footer is 46px in height,
the logo is 45px, it has to be sticked to bottom)
git-svn-id: http://piwigo.org/svn/trunk@5246 68402e56-0260-453c-a942-63ccdbb3a9ee
guetz